What is khushūʿ in prayer? How do I achieve it?

"The time obligation in prayer can be adjusted in cases of necessity, allowing for its substitute. However, sincerity and presence in prayer are essential and cannot be replaced under any circumstances. The obligation of time can be set aside to enhance the benefit of presence. For instance, it is permissible to combine two prayers if an occupation prevents one from being performed at its designated time, such as in the case of a traveler, someone who is ill, or someone occupied with a pressing need."

"Chapter: The second level of Khushu' involves anticipating the flaws of the self and deeds, recognizing the merit of others, and experiencing the subtlety of annihilation. This means being aware of the deficiencies and faults within oneself and one's actions, which naturally humbles the heart. Observing these faults, such as arrogance, vanity, hypocrisy, lack of sincerity, scattered intentions, and failing to perform actions pleasing to اللّٰه, leads to humility."

"desires. Know that Allah observes your innermost soul and gazes upon your heart, accepting from your Salah as much as your khushu, humility, and contrition demonstrate. Worship Him in your prayer as if you see Him, for although you do not see Him, He surely sees you. If your heart is not present and your limbs are restless due to a lack of knowledge of Allah's majesty, imagine a righteous family member observing you to evaluate how you pray."

"Intend withdrawal from prayer, intending greetings upon angels and present worshippers. This is how an individual conducts prayer. The essence of Salah is Khushu, and heart presence throughout recitation and remembrance, with comprehension. Al-Hassan al-Basri, may Allah have mercy on him, stated, Any prayer without heart presence hastens toward punishment."

"Withholding refers to urine and bowels. The tight shoe wearer has a tight shoe. All of these prevent the attainment of proper humility, or khushu'. Likewise for the hungry and the preoccupied. The prohibition against the hungry is understood from the Prophet’s, peace be upon him, saying: “When dinner is served and the prayer is established, start with dinner unless time is short or the mind is at peace."

"As God says, "Neither their meat nor their blood reaches Allah, but what reaches Him is piety from you. This highlights the importance of the heart's presence in prayer. If one argues that requiring the heart's presence for the validity of prayer opposes the consensus of jurists, it is important to note that jurists focus on outward actions."

"if it turns, Satan is present. Thus stands the matter between the servant and his adversary in prayer. Chapter The Servant Strengthens His Presence in Prayer prayer, and engages with his Lord, glorious and exalted, when he conquers his desires and whims. Otherwise, how can a heart overpowered by desires, captivated by whims, and given a foothold by Satan, be free from whispers and thoughts?"